1. Field of the Invention
This invention relates to a data communication network. In particular, it relates to the control of data on data communication networks.
2. Description of the Prior Art
Data communication networks are oftentimes used to interconnect data systems which use the networks to both send and receive data. Typically, such data communication networks may comprise ring transmission paths which are interconnected by ring interface apparatus associated with and used to couple data systems with the ring transmission paths. In such a network data is usually transmitted from an originating data system to the associated ring interface apparatus over a ring transmission path to other ring interface apparatus coupled with a receiving data system.
A data communication network may comprise data systems each connected directly to a single point of a ring transmission path and arranged so that the data systems control the flow of data, hereinafter referred to as data traffic, on the ring transmission path. Other data communication networks are arranged such that a master station connected to a single point of a ring transmission path controls data traffic of the network. In yet other types of data communication networks such as the type of networks described in U.S. Pat. No. 4,554,659, issued Nov. 19, 1985, and in the co-pending application of D. M. Rouse et al., Ser. No. 660,015 filed Oct. 11, 1984, various sectors of the ring transmission paths handle varying amounts of data. Thus, at any one time several sectors of these data communication networks may be handling a large amount of data traffic while other sectors of the network may be handling either medium or small amounts of data traffic.
A problem arises with prior art data communication networks using data systems or a master station connected to a single point in a data communication network to control data traffic in all ring transmission path sectors comprising the network. For example, a master station connected to a single point in a data communication network may lose control of the network if a fault occurs which may open the connection of the master station with the network. In addition, the use of a master station connected to a single point of a data communication network to control data traffic in various sectors of the network increases the data traffic in the ring transmission paths used to convey data between the master station and various sectors of the network.
Accordingly, a need exists for a data communication network arranged for controlling data traffic in various sectors of the network. A need also exists for a data communication network arranged to selectively couple a master station or network control processor with various sectors of transmission paths of the network to control data traffic of the data communication network.